import gzip
from paste.response import header_value, remove_header
from paste.httpheaders import CONTENT_LENGTH
try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO

class GzipOutput(object):


class middleware(object):

    def __init__(self, application, compress_level = 6):
        self.application = application
        self.compress_level = int(compress_level)



    def __call__(self, environ, start_response):
        if ('gzip' not in environ.get('HTTP_ACCEPT_ENCODING', '')):
            return self.application(environ, start_response)
        else:
            response = GzipResponse(start_response, self.compress_level)
            app_iter = self.application(environ, response.gzip_start_response)
            if (app_iter is not None):
                response.finish_response(app_iter)
            return response.write()




class GzipResponse(object):

    def __init__(self, start_response, compress_level):
        self.start_response = start_response
        self.compress_level = compress_level
        self.buffer = StringIO()
        self.compressible = False
        self.content_length = None



    def gzip_start_response(self, status, headers, exc_info = None):
        self.headers = headers
        ct = header_value(headers, 'content-type')
        ce = header_value(headers, 'content-encoding')
        self.compressible = False
        if ((ct and (ct.startswith('text/') or ct.startswith('application/'))) and ('zip' not in ct)):
            self.compressible = True
        if ce:
            self.compressible = False
        if self.compressible:
            headers.append(('content-encoding', 'gzip'))
        remove_header(headers, 'content-length')
        self.headers = headers
        self.status = status
        return self.buffer.write



    def write(self):
        out = self.buffer
        out.seek(0)
        s = out.getvalue()
        out.close()
        return [s]



    def finish_response(self, app_iter):
        if self.compressible:
            output = gzip.GzipFile(mode='wb', compresslevel=self.compress_level, fileobj=self.buffer)
        else:
            output = self.buffer
        try:
            for s in app_iter:
                output.write(s)

            if self.compressible:
                output.close()

        finally:
            if hasattr(app_iter, 'close'):
                app_iter.close()

        content_length = self.buffer.tell()
        CONTENT_LENGTH.update(self.headers, content_length)
        self.start_response(self.status, self.headers)




def filter_factory(application, **conf):
    import warnings
    warnings.warn('This function is deprecated; use make_gzip_middleware instead', DeprecationWarning, 2)

    def filter(application):
        return middleware(application)


    return filter



def make_gzip_middleware(app, global_conf, compress_level = 6):
    compress_level = int(compress_level)
    return middleware(app, compress_level=compress_level)



